BranchMaster.jar can be started by double clicking the jar-file if java is installed, or by letting java start it explicitly with java -jar BranchMaster.jar
Use Java 1.6 or later. Git must be accessible in the path too.
Navigate to a non-bare git-repository, and choose branches to visualize. Choosing more than 10 branches will be very slow, due to the O(n^2) algorithm involving git-commands.